Artificial cardiac valve

ABSTRACT

An artificial cardiac valve made of biocompatible material comprises an  alar valve body and a flap pivotally lodged inside the valve body and possessing linking elements for cooperating with guiding and restraining means provided on an internal side wall of the annular valve body. The flap consists of a disc folded along an axis XX&#39; parallel to one of its diameters through an angle between 0 and 30 degrees in such a way that opening of the valve is effected in two consecutive phases. The first phase corresponds to a rotation of the flap about the contact and hinging point A between a rear part of the flap and a lower edge of the side wall of the valve body until said linking elements abut against the guiding and restraining means. The second phase corresponds to a rotation of about an axis ZZ&#39;  parallel to the axis XX&#39; until the rear part of the flap is parallel to the axis YY&#39; of the annular body.

BACKGROUND OF THE INVENTION

The present invention relates to an artificial cardiac valve.

Numerous artificial cardiac valves employing flap valve devices of theball, disc or flap type in the form of a hemi-disc, already exist.

This is the case, for example, of the valves described in PatentApplications EP 0 176 337 (CARBOMEDICS INC.), EP 0 023 797 (HEMEX INC.),EP 0 039 217 (MITRAL MEDICAL INTERNATIONAL, INC. and EP 0 050 971 (HEMEXINC.).

Furthermore, GB 2 084 299 (HEMEX INC.) describes a cardiac valvecomprising an annular element and a flap pivotally lodged inside saidelement as well as linking elements adapted to cooperate with guidingand restraining means provided on the internal lateral wall of theannular element.

These documents describe in particular valves of the type comprising aflap with single pivoting disc. The disc in question pivots by means ofhinges in the form of protuberances disposed on the inner wall of thebody of the valve and which, due to their configurations andarrangements, are capable of provoking phenomena of thrombosis.

Furthermore, these valves are in a position of complete opening onlywhen the flap has pivoted through a certain angle which is always lessthan 90° about an axis of rotation which merges with its diameter. Infact, the limited angle of 90° does not allow passive closure of thevalve. Consequently, in the position of opening, half of the discconstituting the flap is engaged in the aorta, which may raise problemsof flow and/or space requirements.

Moreover, it is observed that these valves tend to oscillate due to thegreat distance between the axis of rotation and the most remote end ofthe flap.

SUMMARY OF THE INVENTION

The present invention enables these drawbacks to be overcome for thefirst time and in satisfactory manner, by proposing an artificialcardiac valve made of biocompatible material, of the type comprising:

an annular element of axis YY, a flap pivotally lodged inside saidelement and presenting linking elements adapted to cooperate withguiding and restraining means provided on the internal side wall of theannular element, characterized in that said flap is constituted by adisc folded along a line XX' parallel to one of its diameters so as topresent a rear part and a front part located on either side of the lineXX', the rear and front parts forming therebetween an angle greater than150°, with the result that the opening of the valve is effected in twoconsecutive phases, the first phase corresponding to a rotation of theflap about the contact and hinging point A of the rear part of the flapwith the lower edge of the side wall of said element until said linkingelements abut in the guiding and restraining means, and the second phasecorresponding to a rotation about an axis ZZ' parallel to axis XX' untilthe rear part of the flap is parallel to axis YY' of the element.

The cardiac valve of the invention is also characterized in that saidguiding and restraining means are constituted by two symmetrical lateralslideways made in the mass of the element and in which the linkingelements of the flap are movably engaged.

These slideways may be constituted by an arc of circle of centre A andof radius equal to the rear part of the flap, or by hollows comprising,over at least a part of their periphery, straight flanks forming stops.

The linking elements are provided laterally and symmetrically on axisZZ' of the flap and are preferably constituted by two pivots or twoears.

The cardiac valve of the invention therefore presents in position ofopening a so-called rear part parallel to the axis of the element, whichis not produced with the disc valves of the prior art.

On the other hand, the two orifices existing during opening between theflap and the inner wall of the element and constituting the passagewaysfor the flow of blood are of substantially equal dimensions.

In addition, the lateral internal wall of the element of the valvepresents no obstructions for impeding the flow of blood, thus reducingthe risks of thrombosis.

The opening in two phases (proto opening and total opening) by transferof the axis of rotation of the flap advantageously makes it possible toobtain a progressive increase of the flow of blood.

In order to obtain a flow which is even more laminar, the invention alsoprovides the possibility of making the folded disc of the flap with aconcave-convex morphology.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more readily understood on reading the followingdescription accompanied by the attached drawings, in which:

FIG. 1 is a view in perspective of the valve of the invention.

FIG. 2 is a plan view of the valve of the invention in closed (upperhalf-view) and opened positions lower half-view).

FIGS. 3, 4 and 5 are views in section of the valve of the inventionrespectively in three different positions of the flap.

FIG. 6 is a partial plan view of another embodiment of the valve of theinvention.

FIG. 7 is a view in section of an embodiment inspired from that of FIG.6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 2 show the valve of the invention respectively inperspective and in plan view, with the element 1 and the flap 2constituted by a folded disc. Element 1 has a shape which substantiallyfollows the section of flap 2. The lower half-view of FIG. 2 shows flap2 in position of opening whilst the upper half-view shows it in positionof closure.

The disc is folded along an axis XX' parallel to one of its diameters.Axis XX' preferably passes very close to the centre of the disc but mayalso merge with a diameter. Folding of the disc is such that the latterpresents a so-called rear part 3 and a so-called front part 5 located oneither side of axis XX'; the rear and front parts form therebetween anangle greater than 150° and preferably 170°.

In the Figures, the angle between the plane of one of parts (3, 5) andthe extension of the plane of the other is included between 0° and 30°and is preferably 10°.

In the preferred embodiment of the invention as illustrated in theFigures, axis ZZ' constituting the axis of rotation for the second phaseof opening merges with axis XX'. However, in another embodiment of theinvention, rotation for the second phase of opening may be effectedabout an axis ZZ' parallel but distinct from the axis of folding XX'.

In the most general case of axes XX' and ZZ' being parallel withoutmerging, the front and rear parts of the flap 2 are defined with respectto axis ZZ'. In that case, the rear part lies between axis ZZ' and pointA and the front part beyond axis ZZ'; axis XX' being able to be locatedequally well on one side or the other of axis ZZ'.

FIG. 3 shows the valve in section in the position of closure.

In the position of closure, the rear part 3 of the flap 2 is in contactat point A with the lower edge of the side wall 4 of the element 1.

The contact point A performs the role of a hinge during the first phaseof opening. The side wall 4, whilst having a section following that ofthe flap 2, nonetheless presents a partial cut-out 10 in its lower edge,forming a stop at the level of the contact and hinging point A with therear part 3 of the flap 2.

Still in position of closure, the front part 5 of flap 2 rests on a seat6 made on the upper edge of the internal side wall of element 1.

The linking elements of the flap 2 with the element 1 are constituted bytwo symmetrical lateral pivots (7, 7') provided on axis ZZ' here mergedwith axis XX' and on each side of flap 2. These pivots (7, 7') cooperatewith guiding and (restraining) means made on the internal lateral wallof the element 1 and which are preferably constituted by two symmetricallateral slideways (8, 8') made in the mass of the body and correspondingto an arc of circle of centre A and of radius equal to the rear part.Pivots (7, 7') may slide freely and rotate in the slideways (8, 8')during the phases of opening of flap 2.

Element 1 also presents on its internal lateral wall at the level of theupper end of the slideways (8, 8'), two stops (9, 9') adapted to limitand orient rotation of flap 2 during opening.

FIG. 4 shows the valve in section during the first phase of opening,also called proto-opening.

This phase corresponds to a rotation of the flap 2 through some degreesabout the contact and hinging point A of the rear part 3 of flap 2 withthe lower edge of the lateral wall 4 until pivots (7, 7') abut in theupper part of the slideways (8, 8'). The length of the arc of slideways(7, 7') determines the angle of the rotation.

During the whole of the first phase, the ear part 3 of flap 2 is inpivoting contact about point A. This first phase therefore correspondsto a true rotation and not to a translation. At the end of this firstphase, the front part 5 of flap 2 is raised with respect to its seat 6,leaving a passage free for the flow of blood.

FIG. 5 shows the valve in section in the position of complete opening.

At the end of the first phase of opening, pivots (7, 7') abut inslideways (8, 8') and the rear part 3 abuts against the lower faces ofthe stops (9, 9') located at the level of the upper end of the slideways(8, 8'). As the flap still has some degrees of freedom, there isproduced a transfer of the centre of rotation from point A to axis ZZ'here merged with XX'. At that moment, flap 2 pivots about axis ZZ' (hereXX') until the rear part 3 is parallel to axis YY' of the element 1,this corresponding for an angle α of about 10° to a rotation of about60°.

At the end of this rotation, flap 2 is blocked in abutment on thelateral faces of the stops (9, 9'). These faces are inclined by an angleα with respect to axis YY'. In the final position, the front part 5therefore makes an angle of about 10° with axis YY'.

In this embodiment, as axis XX' does not pass through the centre of thedisc, the rear part 3 is slightly smaller (shorter) than the front part5.

Of course, as the opening is fairly rapid the two consecutive phases arevery short and in any case shorter than the phases of opening of thevalves of the prior art, since the angular stroke is less.

Element 1 presents on its external lateral wall means for connection,for example suturing (not shown) with the patient's natural organs.

FIG. 6 is a partial plan view of another embodiment of the invention inwhich the linking elements of flap 2 are constituted by ears or beads(17, 17') forming ball joints and made in the mass of flap 2 adapted tocooperate with guiding and restraining mean constituted by twosymmetrical slideways (18, 18') made in the internal lateral wall ofelement 1.

This embodiment therefore presents more rounded contours than theprevious embodiment, this reducing even more the risks of thrombosis andimproving the flow of blood. Moreover, positioning of the flap in theelement of the valve is facilitated thereby.

FIG. 7 shows a view in section of an embodiment of the valve of theinvention in which the linking elements of flap 2 are identical to thosedescribed with reference to FIG. 6.

These linking elements cooperate with guiding and restraining meansconstituted by two symmetrical lateral slideways in cavity form (28,28') made in the mass of the internal lateral wall of element 1. Thesecavities (28, 28') comprise over at least a part of their periphery,straight flanks (19a, 19b-19'a, 19'b) forming stops and whose role isalso to limit and orient the stroke of flap 2 during opening.

The combination of the cavities (28, 28') and ears (17, 17') correspondsto an articulation of the ball-joint type.

In this embodiment, with the straight flanks (19a, 19b), the stopsbecome unnecessary and are therefore eliminated.

The three positions of flap 2 are shown in FIG. 7.

The orientations of the straight flanks (19a, 19b) with respect to axisYY' are chosen so that the rotation of flap 2 is effected in accordancewith what has been described hereinbefore; i.e. the position of completeopening is obtained when the rear part 3 of flap 2 is parallel to axisYY'.

The valve of the invention may be made of any biocompatible material,for example carbon pyrolite or ceramics.

In addition, the flat folded disc may be replaced by a folded disc withconcave/convex morphology or with any combination between flat, concaveand convex surfaces.

I claim:
 1. An artificial cardiac valve made of biocompatible material,comprising:an annular valve body having a longitudinal axis, said valvebody having guiding and restraining means on an internal sidewallthereof, a flap pivotally mounted inside said valve body and havingmounting ears cooperable with said guiding and restraining means,wherein said flap comprises a disc folded along a transverse lineparallel to a diameter thereof to define a rear part and a front partrespectively located on opposite sides of the transverse line, the rearand front parts forming therebetween an angle greater than 150°, andwherein the opening of the valve is effected in two consecutive phases,a first phase corresponding to a rotation of the flap about a contactand hinging point between the rear part of the flap and a lower edge ofthe internal side wall of said valve body until said mounting ears abutone end of the guiding and restraining means, and a second phasecorresponding to a rotation about an axis parallel to said transverseline until the rear part of the flap is parallel to the longitudinalaxis of the valve body, wherein said guiding and restraining meanscomprise two symmetrical lateral guideways in the annular valve body andin which the mounting ears of the flap are movably engaged, saidsymmetrical lateral guideways corresponding to an arc of a circle havinga center at said contact and hinging point and a radius equal to aradius of the rear part of the flap.
 2. Cardiac valve according to claim1 characterized in that said angle is about 170°.
 3. Cardiac valveaccording to claim 1, wherein said mounting ears of the flap comprisetwo symmetrical lateral pivots provided on said parallel axis. 4.Cardiac valve according to claim 1, wherein said valve body defines twostops for limiting and orienting the two phases of rotation of the flap,and disposed on an internal lateral wall thereof at a level of an upperend of said symmetrical lateral guideways.
 5. Cardiac valve according toclaim 1, wherein said mounting ears of the flap comprise two lateralears forming ball-joints, provided on said parallel axis and integralwith the flap.
 6. Cardiac valve according to claim 1, wherein a lateralwall of said annular valve body has a shape which substantially followsa section of the flap and defines a partial cut-out in a lower edgeforming a stop at a level of the contact and hinging point for the rearpart of the flap.
 7. Cardiac valve according to claim 1, wherein saidvalve body defines a seat on an upper edge of an internal lateral wallto accommodate an outer edge of the front part of the flap in a positionof closure.
 8. Cardiac valve according to any one of the precedingclaims, wherein surfaces of the flap define a concave or convexmorphology.